Age Calculator
Enter your date of birth to get your precise age the way it appears on official documents — complete years, remaining months, and leftover days. You also get fun context: total days lived, the weekday you were born, and how long until your next birthday.
How the Age Calculator works
The calculation follows the standard method used across the US — no shortcuts, no hidden assumptions. Here is exactly what happens behind the scenes:
- Count full years elapsed since the birth date.
- Count remaining full months, then remaining days using actual month lengths.
- Leap days (February 29) are handled automatically by calendar arithmetic.
Frequently Asked Questions
How is age counted legally in the US?
You reach a given age at the start of the day before your birthday anniversary in most legal contexts, though specific rules vary by state document. This calculator reports completed calendar years, matching common usage.
How does the calculator handle February 29 birthdays?
In non-leap years we celebrate the birthday on March 1, consistent with most state statutes. Age in years still increments correctly every 365/366-day cycle.
Can I calculate age at a past or future date?
Yes — change the “age at date” field to any date. It defaults to today and works for birthdays in the past or milestones in the future.
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